Magnetic character generator



Jan- 1967 P. E. OSBORN ETAL 3,302,179

MAGNETIC CHARACTER GENERATQR Filed Dec. 1'7, 1962 I v 2 Sheets-Sheet 1 mm VERTiCAL HORIZONTAL Y COUNTER SWEEP SWEEP GENERATOR GENERATOR EHAS SOURCE 14 l CHARACTER GENERATOR Z 1 MATR\X Q /N\AGNETIC. CORE 1 5 DELAY \k /L\ N a 4 5 k ,64 l T #144 1 i Wuww 4 l l 5\ ,52 55 54 RESET 7 5g 5\ 32 55 34 ,55 AMP. AMP. AMP. An AMP- MR 56 GENERATED 2 3 A 5 CHARACT ER ENG 9575/? E. OBORN INVENTORS I 50 IO CLOCK p U LSE i 2 BY MM Mi sou RCE f A TTORNEY Jan. 31, 1967 OSBORN ETAL 3,302,179

MAGNETIC CHARACTER GENERATOR Filed Dec. 1'7, i962 2 Sheets-Sheet Z.

CLOCK 1n n in 1n 34A 7 m HUUHUL BIA DRWER H I I l l 52A I DR\\/ER H 1 I I PuLsEs 2 65A T CAL DRWER l IF I l l gala l I 5 PERiOD DRWER l I 1 4 I I 55A DRWER l l 5 4sA 44A I r W n n n n n HomZoNTAL I SWEEPS GATES GATES GATES 96 [\OO CHARACTER j CORE DELAY SELECTION SOURCE ARRAY L\NF CLOCK Rme COUNTER RESET Lme 46 PETE/2 E. Osaomv 2 4 CLARENCEWTMREK I NVENTORS A 77'ORNEY United States Patent 3,302,179 MAGNETIC CHARACTER GENERATOR Peter E. Osborn, Addison, and Clarence W. Turek, Glenview, 111., assignors to A. B. Dick Company, Chicago, lll., a corporation of Illinois Filed Dec. 17, 1962, Ser. No. 245,255 4 Claims. (Cl. 340172.5)

This invention relates to character generator circuits and more particularly to improvement therein.

The term Character Generator Circuit is applied to circuits which in response to an input signal can provide an output signal train which when properly displayed on the face of a cathode ray tube represents a character. With the advent of computers, a considerable variety of character generator circuits have been developed since computers provide output signals which have to be converted into a display of some type, or into the printed word. Character generator circuits serve to convert these output signals into a form in which they may be displayed, for example, by cathode ray tube apparatus.

An object of this invention is the provision of a novel and unique character generator circuit.

Another object of this invention is the provision of an inexpensive character generator circuit.

Yet another object of the present invention is the provision of an improved character generator circuit employing magnetic techniques. 7

These and other objects of the invention are achieved in an embodiment of the invention wherein the character generator circuit includes ,a plurality of magnetic cores and a ring counter. The ring counter is coupled to these cores in a manner to derive from them, over the interval of one count cycle, anumber of pulses which, by means of adelay line, are spaced so that upon application to a cathode ray tube system which properly displays these pulses, they provide a desired character pattern.

More clearly stated, a group of cores are reset to a predetermined binary state prior to each count of a ring counter. As the ring counter advances, through its count states, it sets selected ones of the cores, each of which is connected to a separate sensing winding. The sensing windings are connected to different taps on a delay line so that the outputs sensed in response to any given count output from the ring counter are spaced in real time at a single output terminal of the tapped delay line. This output terminal is connected to a cathode ray tube in a manner so that the cathode ray beam is turned on only in response to an output pulse. By proper synchronization of the vertical and horizontal sweeps of the cathode ray tube apparatus, the cathode ray tube displays a character.

The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention itself, both as to its organization and method of operation, as well as addi tional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawings, in which:

FIGURE 1 is a block diagram of an embodiment of a character generator and cathode ray tube apparatus in accordance with this invention.

FIGURE 2 is a circuit diagram of a character generator in accordance with this invention.

FIGURE 3 is a waveshape diagram illustrating pulses which occur in the circuit of FIGURE 2.

FIGURE 4 is a block diagram showing a character generator system in accordance with this invention.

Referring. now to FIGURE 1 there will be seen a block diagram of a character generator and cathode ray 3,392,179 Patented Jan. 31, 1.967

tube arrangement in accordance with this invention. What is shown are the simplest details whereby a character generator in accordance with this invention is connected to cathode ray tube apparatus. As was indicated in the previous brief description, a character which is displayed on the face of the cathode ray tube in accord ance with this invention, will be made up of a number of light dots which are positioned to provide the representation of a character. A ring counter 10 has a count capacity which may be determined by the number of dots desired to be used in the character representation. The ring counter output is applied to a character gen erator matrix 12, which supplies in response thereto, pulses which are spaced in a manner to represent a character on the face of the cathode ray tube, provided that the vertical and horizontal positioning of the cathode ray beam is proper. The output of the character generator matrix is applied to the cathode 14, of the cathode ray tube 16, to turn the beam on whenever a pulse is received from the cathode generator matrix. The cathode ray beam is maintained biased off, except in the presence of such a pulse by a bias source 18, connected to the control grid 20.

The output of the ring counter 10 is also applied to the vertical sweep generator circuits 22, which include synchronizing circuits such that, for each character to be displayed, the cathode ray beam makes one complete vertical traverse in response to one complete count cycle of the ring counter 10. The output of the ring counter 10 is also connected to the horizontal sweep generator 24, which includes synchronizing circuits such that the cathode ray beam makes one complete horizontal traverse in response to each count of the ring counter.

Reference is now made to FIGURE 2 which shows an arrangement for generating a single character in accordance with this invention. Consideration should also be given to FIGURE 3 which illustrates pulses occurring in their proper time relationship in the structure of FIGURE 2. A source of clock pulses30, provides an output which drives the ring counter 10 successively through each one of its count states. The output of each one of the count states of the ring counter is applied to the respective amplifiers 31, 32, 33, 34, and 35. By way of illustration, a five stage ring counter is shown. The size of the ring counter as previously indicated is determined by the number of dots desired to make up a character.

The clock pulses from the clock pulse source 30 drive the ring counter causing it to emit successive pulses-as shown in FIGURE 3, respectively 31A, 32A, 33A, 34A, and 35A. These pulses are distributed in time. The clock pulse source 30 also applies its output to drive a delay line 36. The delay line output is connected to drive a reset amplifier 33. The delay line delays the clock pulse received from the source 30, for a sufficient interval, so that it occurs after the count output responsive to that clock pulse occurs but before the next clock pulse. Thus, the position of the reset pulses 34A, are shown in FIG. 3 occurring at the time just described.

There is provided for each stage of the ring counter, a separate magnetic core respectively 41, 42, 43, 44, and 45. Each one of these magnetic cores preferably has two states of magnetic remanence and may be driven to one of its states by the reset output of the amplifier 38, and to the other of its states by an output from the ring counter. The reset amplifier 38, is connected to all of the cores 41, through 45, by means of a reset winding 46. A separate drive winding respectively 51, 52, 53, 54, and 55, is selectively coupled to the magnetic cores 41 through 45, for applying the outputs from the respective stages of the counter thereto. The coupling of these windings is determined by the character desired to be displayed.

By way of example, it is desired to display the character x. Accordingly, the drive winding 51, which is driven by the first count output of the ring counter, is inductively coupled to the magnetic core 41 and the magnetic core 45. The winding 52, which is driven by the second count state output of the counter, is inductively coupled to cores 42 and 44. The winding 53 applies the third count output of the counter to the magnetic core 43. The winding 54 is inductively coupled to the cores 42 and 44 to drive them to their set states in response to the fourth output from the counter. The winding 55, applies the fifth output of the ring counter to cores 41 and 45, to drive them to their set states.

A reading or sensing winding respectively 61, 62, 63, 64, and 65, is coupled to the respective cores 41 through 45 for the purpose of applying their respective outputs to amplifier 71 through 75. A tapped delay line or a plurality of equal delay lines respectively 81, 82, 83, and 84, are provided The output of amplifier 75 is connected to one end of delay line 84. The output of amplifier 74 is connected to the junction between the other end of delay line 84 and one end of delay line 83. The output of amplifier 73 is connected to the junction of the other end of delay line 83 and one end of delay line 82. The output of amplifier 72 is connected to the other end of delay line 82 which in turn is connected to the one end of delay line 81. The output of amplifier 71 is applied to the other end of delay line 81. This other end of delay line 81 is connected to a terminating resistor 86, and also to the input of a drive amplifier 88. The output of the drive amplifier 88 constitutes the output of the character generator 12 which is applied to the cathode 14 of the cathode ray tube 16, shown in FIGURE 1.

The operation of the system is as follows: All of the cores 41 through 45 are left in their reset state. The first clock pulse drives ring counter 10 to its first count condition whereupon output pulses occur substantially simultaneously on sensing lines 61 and 65. These are amplified and applied to the delay line 81 through 84. The output of the magnetic core 41 is applied to the amplifier 88 substantially instantaneously, but the output from magnetic core 45 has to traverse through all the delay line sections. The delay interval established by all of the delay line sections in series is an interval which is sufficiently less than a clock pulse interval to permit the apparatus to restore itself to receive a succeeding clock pulse. This interval may be seen in FIGURE 3 since it is the interval between pulses 41A and 45A, represented in FIGURE 3 as the pulses which occur at the output of the delay line. Since, as previously indicated, the cathode ray beam makes a complete horizontal traverse during the count interval which is substantially equal to the clock pulse interval, and since the vertical sweep makes a complete traverse over the interval required for the ring counter to complete a count cycle, the cathode ray tube face will display two bright spots along a substantially horizontal line, one of these spots occurring substantially at the beginning of the horizontal trace interval and the other substantially near the end of the horizontal trace interval,

After the first count of the ring counter, a reset pulse 34A occurs, which resets magnetic cores 41 and 45. Thereafter, the second clock pulse causes the ring counter to apply a second count output to the drive winding 52. This drives magnetic cores 42 and 44 to their set states. As a result, sense windings 62 and 64 detect an output which is applied to the delay line at junction between sections 83 and 84 and a junction between sections 81 and 82. As a result, pulses arrive at the output of a character generator which as represented by pulses 42A and 44A in FIGURE 3, when applied to the cathode ray tube will provide the two bright spots which are higher and closer together than the two bright spots initially produced by pulses 41A and 45A.

The continuing operation of the apparatus shown in FIGURE 2 should be clear from the foregoing description. As the counter progresses through its count the cores are reset and then driven to their set states to provide output pulses which are spaced in vertical position in accordance with the count of the ring counter and in horizontal position in accordance with the delay provided by the delay line. It should be appreciated from the foregoing description how a pulse pattern for any desired character may be generated by properly connecting a drive line from a stage of the ring counter to predetermine ones of the magnetic cores in accordance with the required vertical position for those pulses as far as the count selection is concerned, and in accordance with the required horizontal position of those pulses as far as the selected cores are concerned.

Where more than one character is to be generated, one may use more than one set of cores but preferably, a single set of cores may be used with a gating system which selects a set of drive windings for a character which it is desired to display. An arrangement for doing this is shown in FIGURE 4. The ring counter 10 is driven by the clock source 30 as before. Reset pulses are applied to the reset winding 46, which is coupled to all the cores of the core array as before. All of the outputs of the ring counter are applied to gate sets 90, 9'2, 94, there being as many gate sets as there are separate sets of windings associated with the separate characters. Thus for example, in FIGURE 4, there are three gate sets shown respectively, 90, 92, 94. For the five count ring counter and five drive windings, each gate set will comprise five different gates.

In order to open a selected one of the gate sets, a character selecting source 96 is employed. The character selecting source applies an enabling signal to all the gates in one of the sets, 90, 92, 94, in accordance with the character desired to be displayed. The selected set of gates connects the selected set of drive windings to the ring counter output whereby selected ones of the cores in the core array 98, are driven in response to the output of the ring counter. The output of the core array 98 is applied to the delay line 100.

While an array of five cores only is shown in FIGURE 2, it will be understood from the foregoing description that as many cores may be employed as the number of dots desired to make up a character. Of course the size of the ring counter increases with the size of the cores as do the number of sections of delay line. While the foregoing description showed how the letter x was created, using this embodiment of the invention, it should be apparent how other letters may also be created. For example, to create the signals for forming the letter H," the first count output would be applied to a drive winding coupled to cores 41, and 45. The respective second, fourth, and fi th count outputs would be applied by separate drive windings to drive cores 41 and 45. The third count output would be coupled by a drive winding to drive every core to provide the cross bar in the H.

To form the letter R, the first and second and fourth count outputs of the counter would be applied to cores 41 and 45 by the respective drive windings. The third and fifth count outputs of the counter would be applied by the respective drive windings to all the cores of the counter.

The foregoing examples it is believed should make clear the winding pattern scheme required for representing different characters. The winding pattern table may be made up by first establishing a 5 x 5 matrix, determining at which points in the matrix the brightness pips should occur on the cathode ray tube, and analogizing the counts of counter as the x axis and the cores as they are physically positioned as the y axis, the required winding pattern is readily seen.

There has accordingly been described and shown herein above, a novel, useful, and rather simple character generator.

We claim:

1. In a character display system of the type wherein characters are formed on a display device as a plurality of successive adjacent lines along each of which are spots displaced from one another, apparatus for providing signals from which said spots are derived comprising a counter having a number of different count stages said number equalling the total number of lines on said character display, each count stage being associated with a different line, means for driving said counter to cause each count stage to produce an output in succession, a plurality of magnetic cores each of which has a first and a second state of magnetic remanence, the number of magnetic cores in said plurality equalling the total number of spots which can occur along a line, each core being associated with a spot on every line, means responsive to the output of a count stage for driving from their first to their second states the ones of said cores associated with the spots required on the line with which said count stage is associated, means for deriving a separate output signal from each core driven by said count stages output, and means for ordering said output signals in a signal sequence having the same relative spacing as the spacing of the spots on the line with which said count stage is associated.

2. In a character display system of the type wherein characters are formed on a display device as a plurality of successive adjacent lines along each of which are spots displaced from one another, apparatus for providing signals from which said spots are derived comprising a counter having a number of different count stages said number equalling the total number of lines on said character display, each count stage being associated with a different line, means for driving said counter to cause each count stage to produce an output in succession, a plurality of magnetic cores each of which has a first and a second state of magnetic remanence, the number of magnetic cores in said plurality equalling the total number of spots which can occur along a line, each core being associated with a spot on every line, a separate drive winding for every count stage of said counter, each of said drive windings being connected to a different count stage for receiving an output therefrom, each of said drive windings being coupled for driving from their first to their second states the magnetic cores associated with the spots along the line with which said count stage is associated, a reset winding coupled to all said cores for driving them from their second to their first states of magnetic remanence, means for applying driving current to said reset winding before said counter is advanced to each successive count state, a separate sensing winding coupled to each magnetic core for deriving an output signal from when said core is driven from its first to its second state of magnetic remanence, and means to which all of said sensing windings are connected for ordering said output signals in a signal sequence having the same relative spacing as the spacing of the spots on the line with which a count stage producing the core driving output is associated.

3. In a character display system as recited in claim 2 wherein said means to which all of said sensing windings are connected for ordering said-output signals comprises a delay line having a plurality of taps therealong,

and means connecting a different one of said sense windings to a different one of said taps to provide a desired signal sequence at-one end of said delay winding.

4. In a character display system of the type wherein characters are formed on a display device as a plurality of successive adjacent lines along each of which are spots displaced from one another, apparatus for providing signals from which said spots are derived comprising a counter having a number of different count stages, said number equalling the total number of lines on said character display, each count stage being associated with a different line, means for driving said counter to cause each count stage to produce an output in succession, a plurality of magnetic cores each of which has a first and a second state of magnetic remanence, the number of magnetic cores in said plurality equalling the total number of spots which can occur along a line, each core being associated with a spot on every line, a plurality of sets of core drive windings, each different set being associated with a separate character desired to be displayed, each set of drive windings containing a drive winding for each line of spots required to represent the associated character, a plurality of sets of gates, each different set of gates being associated with a separate character desired to be displayed, each different set of gates containing as many gates as there are count stages, means connecting a different gate in each set to a difierent count stage to receive output therefrom, means connecting each set of gates to the set of core drive windings associated with the same character, to receive a drive from the set of gates which is closed, means coupling each drive winding in each set to those magnetic cores which are associated with the spots along the line with which the count stage which drives that drive line is associated, the coupling of said core drive windings on said magnetic cores being made for driving said cores from their first to their second states of magnetic remanence, a source of character selection signals, means for applying signals from said character signal selection source to a set of gates associated with the selected character for closing that set of gates, a reset winding coupled to all the cores for driving them from their second to their first states of magnetic remanence, means for applying driving current to said reset winding before said counter is advanced to each successive count state, a separate sensing winding coupled to each magnetic core for deriving an output signal therefrom when said core is driven from its first to its second state of magnetic remanence, and means to which all of said sensing windings are connected for ordering said output windings in a signal sequence having the same relative spacing as the spacing of the spots on the line with which a count stage producing the core driving output is associated.

References Cited by the Examiner UNITED STATES PATENTS 1/1960 Gordon et al. 340-174 l/1962 Auerback et al. 340l72.5

OTHER REFERENCES ROBERT C. BAILEY, Primary Examiner.

R. M. RICKERT, Assistant Examiner. 

1. IN A CHARACTER DISPLAY SYSTEM OF THE TYPE WHEREIN CHARACTERS ARE FORMED ON A DISPLAY DEVICE AS A PLURALITY OF SUCCESSIVE ADJACENT LINES ALONG EACH OF WHICH ARE SPOTS DISPLACED FROM ONE ANOTHER, APPARATUS FOR PROVIDING SIGNALS FROM WHICH SAID SPOTS ARE DERIVED COMPRISING A COUNTER HAVING A NUMBER OF DIFFERENT COUNT STAGES SAID NUMBER EQUALLING THE TOTAL NUMBER OF LINES ON SAID CHARACTER DISPLAY, EACH COUNT STAGE BEING ASSOCIATED WITH A DIFFERENT LINE, MEANS FOR DRIVING SAID COUNTER TO CAUSE EACH COUNT STAGE TO PRODUCE AN OUTPUT IN SUCCESSION, A PLURALITY OF MAGNETIC CORES EACH OF WHICH HAS A FIRST AND A SECOND STATE OF MAGNETIC REMANENCE, THE NUMBER OF MAGNETIC CORES IN SAID PLURALITY EQUALLING THE TOTAL NUMBER OF SPOTS WHICH CAN OCCUR ALONG A LINE, EACH CORE BEING ASSOCIATED WITH A SPOT ON EVERY LINE, MEANS RESPONSIVE TO THE OUTPUT OF A COUNT STAGE FOR DRIVING FROM THEIR FIRST TO THEIR SECOND STATES THE ONES OF SAID CORES ASSOCIATED WITH THE SPOTS REQUIRED ON THE LINE WITH WHICH SAID COUNT STAGE IS ASSOCIATED, MEANS FOR DERIVING A SEPARATE OUTPUT SIGNAL FROM EACH CORE DRIVEN BY SAID COUNT STAGES OUTPUT, AND MEANS FOR ORDERING SAID OUTPUT SIGNALS IN A SIGNAL SEQUENCE HAVING THE SAME RELATIVE SPACING AS THE SPACING OF THE SPOTS ON THE LINE WITH WHICH SAID COUNT STAGE IS ASSOCIATED. 